1. Technical Field
The present invention relates to a method and apparatus for controlling the power shutdown of an electrical component. More particularly, the invention relates to a method and apparatus for selectively inhibiting the power shutdown of an electrical component based upon a maximum number of safe power shutdowns performed to date.
2. Background of the Invention
Research indicates that a substantial amount of energy consumed by devices such as computers, computer monitors, and other electrical devices is consumed when the devices are not in use. It has therefore been common to include in such devices the capability of automatically shutting down the device when an extended period of non-use is detected. A typical period of non-use triggering such a shutdown is 30 minutes. In computer systems, such a shutdown is typically preceded by a state-saving operation so that the state of the system may be restored upon a subsequent startup.
Executive Order no. 12845, of Apr. 21, 1993 requires that federal agencies procure equipment that complies with the Environmental Protection Agency (EPA) "Energy Star" program, of which the automated power shutdown is a part. The changes to federal procurement process alone are estimated to save several million dollars in energy consumption and substantially reduce air pollutant and greenhouse gas emissions from electric utilities.
Although the automated shutdown has the benefit of reducing power consumption, it increases the number of power-on transitions experienced by the device, because use of the device following the shutdown requires re-application of power to the shutdown device prior to use. A device having a 30-minute trigger time, and that is frequently but intermittently used, for example, may experience between 20 to 40 power-on transitions a day. This is a considerable increase over a more typical one power transition per day, or per longer period, which would be in effect without the automatic shutdown capability.
It is known that the lifetime of electrical equipment is shortened by repetitive power-on transitions. Therefore, it is desirable to permit automated power shutdowns to save power, while managing the number of power shutdowns to prevent them from negatively impacting the lifetime of the equipment being powered down.